The present invention relates to a buzzer for a portable communication device such as a portable telephone and a beeper.
The portable communication device is operated by the power of a storage battery as a main source of electricity having a large capacity under normal conditions. In such a device, it is necessary to provide a backup source for preventing a memory from erasing data such as telephone numbers stored therein, if the voltage of the main source, or the main source is cut off. In addition, it is necessary to provide an auxiliary source to operate a buzzer even if the main source is cut off.
As an auxiliary source, a disk type small battery is used. On the other hand, as a sound source for calling sound and a warning sound of the portable communication device, a very small buzzer is used.
In general, the auxiliary battery is mounted on a source portion of a substrate, and the buzzer is attached to a position necessary for the portable communication device, which positions have no relation with each other.
Referring to FIG. 7 showing a prior art, a buzzer 21 is disposed on a substrate (not shown) regardless of a battery 22. The battery 22 is set in an insulation case 23 mounted on the substrate. The battery is connected to a control circuit for a memory and the buzzer through contact plates 24 and 25 connected to a circuit on the substrate. The battery is a storage battery charged at the same time as the charging of the main battery, and provided as a backup battery or a source for the buzzer.
In the prior art, since the battery and the buzzer are independently disposed, it is necessary to form a space on the substrate for mounting the battery, resulting in increasing of the size of the substrate and hence the size of the portable communication device.
Furthermore, the buzzer 21 and the case 23 for the battery 22 are manufactured in separate manufacturing processes, which causes the manufacturing and assembling costs to increase.